This article explains how to build an app with a Streetview button. This button allows users to click on the map to open a new StreetView tab in their browser
First, click the Add resources [+] button in the main menu. Then, select Mapping Application. Give a Name of your app and select a Map from your Library.
Then, in Source area, put this code snippet. It will add an action button on the map. The URL option let you set a link template with a latitude/longitude user click.
Finally, we will change the default icon for a StreetView icon from FontAwesome library with this other code snippet just after mappyOption instruction.